Molded articles comprising polypropylene are used for various applications because of their excellent stiffness, heat resistance and surface gloss.
It has been known in the art to use polypropylene compositions containing polypropylene and an ethylene copolymer, in order to improve impact resistance of polypropylene.
For example, JP 10-87714A discloses a process for producing a propylene polymer composition, which process comprises the steps of producing a propylene polymer with a non-metallocene catalyst, and then producing an elastomer with a catalyst consisting of at least a metallocene compound and a cocatalyst component.
However, a polypropylene composition disclosed in the above patent literature is not necessarily sufficient in its stiffness and impact resistance, and therefore it has been desired to improve stiffness and impact resistance of a polypropylene composition.